Silicon photonics is a platform for potentially revolutionary advances in the fields of telecommunications, data communications, medical technology, security, and sensing. Silicon photonics has the potential to realize small, highly integrated, photonics sub-systems that leverage off the decades of silicon fabrication experience, technology and scalability to gain access the full potential of the silicon platform, i.e. silicon photonics for high-speed signaling and sensing, and complimentary metal-oxide semiconductor (CMOS) electronics for subsequent logical operations and computations. Such multi-chip integration also allows for the bridging of different functional technologies, such as micro-electro-mechanical systems (MEMS), III-V materials, non-CMOS application-specific integrated circuits (ASIC) etc.
In a typical silicon photonic package with multi-chip integration scheme, including a V-groove photonic integrated circuit (PIC) chip, a trans-impedance amplifier (TIA) chip and a driver chip, conducting wires (i.e., wire bonding) are used as chip-to-chip and chip-to-substrate interconnections as a flexible, low cost process that is able to accommodate the manufacturing process variations of semiconductor chips as well as those of the substrates. However, with wire bonding and long interconnect paths, the performance of the integrated multi-chip semiconductor devices will have higher parasitic inductance and poorer electrical performance. Flip-chip integration of PIC chip can provide shorter interconnect paths. However, the V-grooves for optical fiber connections are on the active side of the PIC chip, which makes flip-chip integration of such PIC chips challenging because the V-grooves are not easily accessible for optical fiber connections after the flip-chip assembly of the PIC chip.
Thus, it is desirable to provide shorter interconnect paths for the multi-chip semiconductor devices and yet be able to accommodate the various manufacturing process variations, as well as deliver smaller packaging footprints with improved electrical performances.